import Geometry.*;
import java.awt.*;

/**
 * Summary description for ParticleSystem.
 */

public class ParticleSystem
{
	class Particle
	{
		Vector3 position;
		Vector3 velocity;
		double age=-1;
		double lifespan;
		double size;

		double[] startColor = new double[4];
		double[] endColor = new double[4];
		double[] color = new double[4];
	}

	boolean explosion=false;
	boolean rings=false;

	public ParticleSystem(int maxParticles)
	{
		particles = new Particle[maxParticles];
		for(int i=0; i<maxParticles; i++)
		{
			particles[i] = new Particle();	
		}

		//Set defaults
		position = new Vector3(0, 0, 0);
		direction = (new Vector3(1,0.2,0)).normalize();
		up = new Vector3(0, 1, 0);

		setFountain();
		
		cp = up.cross(direction).NORMALIZE();
	}

	public void setExplosion()
	{
		rings = false;

		direction = (new Vector3(0,1,0)).normalize();
		up = new Vector3(1, 0, 0);

		explosion = true;
		gravity = new Vector3(0, -1, 0);
		minSpeed = 90;
		maxSpeed = 90;
		flowRate = 350; //60
		minAngle = 0;
		maxAngle = 90;
		minRotate = 0;
		maxRotate = 90;
		minLife = 5;
		maxLife = 5;
		minSize = 10; 
		maxSize = 20;

		flowResidue = 350;
///		minStartColor = new double[]{ 0, 20/255.0, 180/255.0, 240/255.0};
//		maxStartColor = new double[]{ 0, 20/255.0, 200/255.0, 255/255.0};
//		minEndColor = new double[]  { 240.0/255.0, 20/255.0, 0, 240/255.0 };
//		maxEndColor = new double[]  { 255.0/255.0, 40/255.0, 0, 255/255.0 };

		//minStartColor = new double[]{ 230/255.0, 200/255.0, 70/255.0, 240/255.0};
		//maxStartColor = new double[]{ 252/255.0, 219/255.0, 97/255.0, 240/255.0};
		//minEndColor = new double[]  { 121/255.0, 58/255.0, 12/255.0, 240/255.0 };
		//maxEndColor = new double[]  { 140/255.0, 58/255.0, 30/255.0, 240/255.0 };

		minStartColor = new double[]{ 255/255.0, 105/255.0, 0/255.0, 240/255.0};
		minStartColor = new double[]{ 255/255.0, 105/255.0, 0/255.0, 240/255.0};
		
		minEndColor = new double[]  { 243/255.0, 242/255.0, 0/255.0, 240/255.0 };
		minEndColor = new double[]  { 243/255.0, 242/255.0, 0/255.0, 240/255.0 };
	}

	public void setFountain()
	{
		explosion = false;
		rings = false;

		gravity = new Vector3(0, -5, 0);
		direction = (new Vector3(1,0.2,0)).normalize();
		up = new Vector3(0, 1, 0);
		minSpeed = 30;
		maxSpeed = 50;
		flowRate = 15; //60
		minAngle = 0;
		maxAngle = 30;
		minRotate = 90;
		maxRotate = 90;
		minLife = 15;
		maxLife = 30;
		minSize = 5; 
		maxSize = 20;

		flowResidue = 10;
		minStartColor = new double[]{ 0, 20/255.0, 180/255.0, 240/255.0};
		maxStartColor = new double[]{ 0, 20/255.0, 200/255.0, 255/255.0};
		minEndColor = new double[]  { 240.0/255.0, 20/255.0, 0, 240/255.0 };
		maxEndColor = new double[]  { 255.0/255.0, 40/255.0, 0, 255/255.0 };
	}

	public void setRings()
	{
		rings = true;
		explosion = false;

		direction = (new Vector3(0,1,0)).normalize();
		up = new Vector3(1, 0, 0);

		gravity = new Vector3(0, -1, 0);
		minSpeed = 45;
		maxSpeed = 60;
		flowRate = 350; //60
		minAngle = 0;
		maxAngle = 90;
		minRotate = 0;
		maxRotate = 90;
		minLife = 10;
		maxLife = 15;
		minSize = 10; 
		maxSize = 20;

		flowResidue = 350;
		minStartColor = new double[]{ 20/255.0, 240/255.0, 10/255.0, 0};
		maxStartColor = new double[]{ 20/255.0, 255/255.0, 50/255.0, 0};
		minEndColor = new double[]  { 80.0/255.0, 10/255.0, 100/255.0, 240/255.0 };
		maxEndColor = new double[]  { 100.0/255.0, 10/255.0, 120/255.0, 255/255.0 };

	}

	double random(double _start, double _end)
	{
		double start, end;
		if( _start > _end )
		{
			start = _end;
			end = _start;
		}
		else
		{
			start = _start;
			end = _end;
		}

		return Math.random() * (end - start) + start;
	}

	Vector3 cp;

	private void resetParticle(Particle particle)
	{
		particle.position = this.position.copy();
		
		double angle = random(minAngle, maxAngle);
		double rotation = random(minRotate, maxRotate);
		double speed = random(minSpeed,maxSpeed);

		//Vector3 cp = up.cross(direction).NORMALIZE();

		if(explosion)
		{
			if(particle.velocity == null)
				particle.velocity = new Vector3();
			particle.velocity.SET(random(-1,1), random(-1,1), random(-1,1));
			particle.velocity.NORMALIZE();
			particle.velocity.MUL(speed);
		}
		else if(rings)
		{
			if(particle.velocity == null)
				particle.velocity = new Vector3();			
			
			if(random(-1,1) > 0)
			{
				particle.velocity.SET(random(-1,1), random(-1,1), 0);
			}
			else
			{
				particle.velocity.SET(random(-1,1), 0, random(-1,1));
			}

			particle.velocity.NORMALIZE();
			particle.velocity.MUL(speed);	
		}
		else
		{
			Matrix4x4 rotateMatrix = 
				(new Matrix4x4()).rotate(cp, rotation).rotate(direction, angle);
			//Matrix4x4 rotateMatrix = 
			//	(new Matrix4x4()).rotate(direction, rotation).rotate(cp, angle);
		
			//particle.velocity = rotateMatrix.mul(direction).mul(speed);
			particle.velocity = rotateMatrix.mul(direction);
			particle.velocity.MUL(speed);
		}

		particle.age = 0;
		particle.size = random(minSize, maxSize);
		particle.lifespan = random(minLife, maxLife);

		for(int k=0; k<4; k++)
		{
			particle.startColor[k] = random(minStartColor[k], maxStartColor[k]);
			particle.endColor[k] = random(minEndColor[k], maxEndColor[k]);
		}

		/*
		particle.startColor[1] = random(minStartColor[1], maxStartColor[1]);
		particle.startColor[2] = random(minStartColor[2], maxStartColor[2]);
		particle.startColor[3] = random(minStartColor[3], maxStartColor[3]);
		particle.endColor[1] = random(minEndColor[1], maxEndColor[1]);
		particle.endColor[2] = random(minEndColor[2], maxEndColor[2]);
		*/
		
	}

	double lerp(double x, double y, double a)
	{
		return a*x + (1-a)*y;
	}

	private void updateParticle(Particle particle, double timeDelta)
	{
		if( particle.age == -1 )
			return;

		particle.age += timeDelta;

		if( particle.age >= particle.lifespan )
		{
			particle.age = -1;
			return;
		}

		/*particle.position = */ particle.position.ADD(particle.velocity.mul(timeDelta) );
		/*particle.velocity = */ particle.velocity.ADD(gravity.mul(timeDelta) );
		
		double interp = particle.age / particle.lifespan;
		for(int i=0; i<4; i++)
			particle.color[i] = lerp(  particle.endColor[i], particle.startColor[i],interp );
	}

	private void renderParticle(ThreeDimensionalApplet app, Particle particle)
	{
		app.pointSize((int)Math.round(particle.size));
		
		//app.color(new Color(255, 0, 0));
		app.color4d(particle.color[0], particle.color[1], particle.color[2], particle.color[3]);
		app.vertex(particle.position);
	}

	public void update(double timeDelta)
	{
		double particlesNeeded = timeDelta * flowRate + flowResidue;
		for(int i=0; i<particles.length; i++)
		{
			updateParticle(particles[i], timeDelta);
			if( particles[i].age == -1 && particlesNeeded >= 1 )
			{
				resetParticle(particles[i]);
				particlesNeeded = particlesNeeded - 1.0;
			}
		}

		flowResidue = particlesNeeded;
	}

	public void render(ThreeDimensionalApplet app)
	{
		app.enable(app.RENDER_BLENDING);
		app.blendFunc(app.RENDER_SRC_ALPHA, app.RENDER_ONE_MINUS_SRC_ALPHA);
		//app.blendFunc(app.RENDER_SRC_ALPHA, app.RENDER_ONE);
		app.disable(app.RENDER_LIGHTING);
		app.enable(app.RENDER_TEXTURE);
		app.pointSize(4);
		app.begin(app.RENDER_POINTS);
		for(int i=0; i<particles.length; i++)
		{
			if( particles[i].age != -1 )
				renderParticle(app, particles[i]);
		}
		app.end();
		app.disable(app.RENDER_TEXTURE);
		app.disable(app.RENDER_BLENDING);
	}

	Vector3 position;
	Vector3 up;
	Vector3 direction;
	Vector3 gravity;
	double minSpeed, maxSpeed;

	double flowRate, flowResidue=0;
	double minAngle, maxAngle; //between direction and up
	double minRotate, maxRotate; //about the direction
	double minLife, maxLife;
	double minSize, maxSize;

	double minStartColor[], maxStartColor[];
	double minEndColor[], maxEndColor[];

	int maxParticles;
	int aliveParticles;
	Particle particles[];
}